Filling up your tank may be an easy thing to do, but the process by which oil is discovered is anything but. The creation of oil is itself an amazing process – beginning with the death millions of years ago of very small plants and animals, with the organisms sinking into and mud. These remains mixed with sediment to form what’s known as source rock. And when the source rock is pressured and heated by new sedimentary layers, it distils the remains of the organisms into natural gas and crude oil.

These fossil fuels then shift into what’s called reservoir rock. Inside the reservoir rock (limestone or sandstone) are porous areas, and it’s in these pores that the oil embeds itself. But these pores must be interconnected, so that oil can flow between them, for the rock to be useful for oil hunters; this is because the hydrocarbons must be able to make this movement for an oil drilling operation to be worthwhile. In the meantime, the oil lies in wait in the rock until someone comes along to discover them.

Enter the geologist, whose job it is to seek out and uncover deposits of oil. Geologists do this by looking for signs of conditions where oil may be found – hunting for indicators of the source rock and reservoir rock where the oil becomes entrapped.

Now, back in the early days of oil exploration in the 19th century, these oil-scouring scientists would examine surface features in their quest for black gold, features such as rock and soil types; other times they’d extract a small section of the earth through shallow drilling into the Earth’s crust to retrieve what’s known as a core sample.

These above-ground oil-searching methods continue to be used today. But geologists have, of course, added some new tools to their energy exploration toolbox. These include the use of satellite imagery to help find surface terrain and rocks. They also look for minor changes in the planet’s gravitational field that can be the sign of oil. And they also use a tool known as a magnetometer, which measures not the Earth’s gravity but its magnetic field for telltale signs of oil.